In the right transept is the Bichi Chapel, commissioned by Antonio Bichi and dedicated to his son-in-law, Cristoforo Bellanti. The chapel, built between 1490 and 1494, was richly decorated with a painting cycle, part of which is still visible. The altar, which now hold a canvas of Saint Christopher painted in 1755 by Niccolò Franchini, was originally adorned with a polyptych (now in Berlin) by the painter Luca Signorelli from Arezzo, which acted as a support for the wooden sculpture of Saint Christopher made by Francesco di Giorgio Martini, now in the Louvre. In the lunettes of the ceiling are the Tiburtine Sibyl and the Erithrean Sibyl by Signorelli, while the side walls are frescoed with scenes of the Birth of the Virgin and the Nativity of Christ, both by Francesco di Giorgio.
The decoration of the chapel is brought to a fitting conclusion by the beautiful fifteenth-century majolica tile floor, made by Pietro and Niccolò Mazzaburroni.